The U.S. State Department questioned the Chinese government about a cyberattack that had temporarily shutdown Change.org after the site held a petition urging Chinese authorities to release artist Ai Weiwei from custody.

U.S. deputy assistant secretary Daniel Baer raised concerns about the attack in April with China's foreign ministry, according to an official letter sent from the State Department to U.S. Rep. Rosa DeLauro. Change.org obtained a copy of the letter and released it on Tuesday.

The nature of those talks is still unclear. The U.S. Embassy in Beijing said it had no current information on the matter and deferred to the State Department. China's foreign ministry has yet to respond to a request for comment.

DDoS attacks can do this by using hundreds or thousands of hacked computers to drive enough traffic to a website. The data will become so overwhelming that the site will become inaccessible to normal users.

Change.org said the DDoS attack was its first. The site's founder Ben Rattray believed the incident was connected to an online petition calling for the release of Chinese artist Ai Weiwei, who is still under arrest. When the attack occurred in April, the petition had attracted about 100,000 people. Now the petition has more than 142,000 signatures.

Ai Weiwei's arrest followed the detainment of other human rights activists in China after online postings were made starting this February calling for a "Jasmine revolution" against the Chinese government. Since then, Authorities have increased their censorship of the Web, and have been quick to block searches for sensitive words relating to protest actions.

China has been named the country of origin for several other cyber attacks. This month, Google said it had disrupted a targeted phishing campaign meant to break into the Gmail accounts of government officials, political activists and military personnel. Google said the cybercampaign had originated from Jinan, China.

Previously, the search giant was the victim of another attack coming out of China back in 2009 that was aimed at accessing the Gmail accounts of Chinese human rights activists.

China, however, has denied it sponsors any cyber attacking, and claims that the country is also a victim of hacking attempts.

To comment on this article and other PCWorld content, visit our Facebook page or our Twitter feed.